Helicopter rotor control



Oct. 30, 1951 H. D. HARBY 2,573,016 HELICOPTER ROTOR CONTROL 7 FiledDec. 10, 1945 5 Sheets-Sheet 1 IN V HV TOR.

H14? OLD D. HARDY Oct. 30, 1951 H. D. HARBY 2,573,016

HELICOPTER ROTOR CONTROL Filed Dec. 10, 1945 5 Sheets-Sheet 2 F 2INVENTOR.

f/HROLD D. HARE Y H. D. HARBY HELICOPTER ROTOR CONTROL Oct, 30, 1951 5Sheets-Sheet 5 Filed Dec. 10, 1945 v 7 .Y 1 R fl mm Z, V 8 D m a P M i 79 B 2% m u; 1 J f 6 z y/ An l :5. T 9 I I I 4 m j k a w m j 1 7 u 3 i l2 m Oct. 30, 1951 H. D. HARBY 2,

HELICOPTER ROTOR CONTROL Filed Dec. 10, 1945 5 sheets-sheet 4 IN V ENTOR. fimzow 0. HAR

Oct. 30, 1951 H. D. HARBY HELICOPTER ROTOR CONTROL 5 Sheets-Sheet 5Filed Dec. 10, 1945 v INVEN TOR. HH/EOLD DHAKBY Patented Oct. 30, 1951UNITED STATES PATENT OFFICE HELICOPTER ROTOR CONTROL Harold D. Harby,Los Angeles, Calif.

Application December 10, 1945, Serial No. 634,001

Claims.

This invention relates to aircraft, and particularly pertains to ahelicopter.

During the development of aircraft, which is characterized as beingheavier than air, numerous attempts have been made to produce anairplane which could ascend directly from the ground and could travel inany horizontal direction, and thereafter descend directly to the ground,thus eliminating the use of long runways and providing a simple mobilecraft which could easily travel in the air, and which could land andtake off without hazard. In designing aircraft of this particular typethe problems have been made extremely complicated due to the fact that astructure was required using propellers which of necessity must bedriven continuously, and which propellers require manipulation toestablish and vary cyclic, total and differential pitch. Variousattempts have been made to solve these problems in a simple manner, butin most instances heretofore it has been necessary to mount thepropeller blades so that they could be manipulated individually andcollectively with relation to a driving hub, which hub is driven by acomplicated mechanism and along a devious path of power transmission. Itis desirable, therefore, to provide an aircraft of the helicopter typewhich will be simple and sturdy in its construction and will not requirea complicated control mechanism. It is the principal object of thepresent invention, therefore, to provide an aircraft of the helicoptertype Within Which propellers are used having rigid blades carryingarticulate members adapted to be easily manipulated without reference tothe driving mechanism, and which blades are fitted with simple controlmeans which may be used to establish or vary the effective cyclic totaland differential pitch of the blades.

The present invention contemplates the provision of an airplane framestructure which may be suitably housed within a, fuselage, and whichstructure supports a power unit, a vertical mast including twooppositely driven power shafts, each carrying a hub upon which radialblades are rigidly fastened, each of which blades is fitted with anarticulate trailing edge, the structure being also supplied with powertransmission means for the mast drive shafts and simple control meansfor varying the effective pitch angles of the blades as required inattaining cyclic total and differential pitch.

The invention is illustrated by Way of example in the accompanyingdrawings in which:

Figure 1 is a view in perspective showing the general arrangement of theessential parts of the 2 present invention with the fuselage omitted forconvenience in disclosure.

Fig. 2 is a view in elevation with parts broken away showing the mastand the power and control units associated therewith.

Fig. 3 is a view in central vertical section through the structure shownin Fig. 2 with parts broken away for the sake of convenience, andfurther indicating the details of construction of the drive and control.

Fig. 4 is a View in transverse section through the mast as seen on theline 4-4 of Fig. 2 and shows the details of construction of themasthead.

Fig. 5 is a fragmentary View in plan showing the mast-head and one ofthe propeller blades associated therewith.

Fig. 6 is an enlarged view in transverse section through one of thepropeller blades, as shown on the line 6-ii of Fig. 5, and discloses thearticulate trailing edge.

Fig. '7 is an enlarged fragmentary view in transverse sectionshowing thehinge mounting for the articulate trailing edge of a propeller blade, asseen on the line 'l'! of Fig. 5.

Fig. 8 is an enlarged fragmentary view showing the connection betweenthe mast-head and one of the propeller blades.

Fig. 9 is a view in vertical section showing the blade connection asseen on the line 99 of Fig. 8.

Fig. 10 is an enlarged view in horizontal section and elevation showingthe mast and the top of the control mechanism, as seen on the line l0lllof Fig. 2.

Fig. 11 is a view through one of the cam structures of the controlmechanism, as seen on the line llll of Fig. 10.

Fig. 12 is an enlarged fragmentary view showing a cable pulley, as seenon the line l2l2 of Fig. 11.

Fig. 13 is a fragmentary View in vertical section and elevation througha portion of the pitch control mechanism, as seen on the line l3-l3 ofFig. 2.

Fig. 14 is a view showing one of the pitch control star wheels, as seenon the line M-M of Fig. 13.

Referring more particularly to the drawings, I0 indicates a framestructure. It is to be understood that this frame may be built up asdesired and the structure is merely illustrated by Way of example. Theframe is here shown as comprising opposite parallel side rails ll. Theyare connected by a rear transverse rail l2 and a forward transverseelement I3. The forward transverse element I3 is here shown as providedwith diagonal brace members I4 to give a rigid support for a wheel forkI5. This fork carries front landing wheels I6 which, with a rear landingwheel I1, provides the running gear for the vehicle. The wheel fork Ihas a horizontal central portion I8 which is secured to the side framemembers I I by fittings I9 which proj ect upwardly from the. tWosideframe members I I.

Mounted upon the rear portion of the frame is a power plant unit 20. Thedetails of construction of this unit need not be explained, other thanto state that a suitable prime mover forms a part thereof and isconnected directlyor through a transmission gear set with a drive shaft2I, here shown as extending forwardly from the unit 20. The drive shaftj-2I. transmits .gpowerto a combined drive and pitch control unitgenerally indicated at 22. This is disposed-between and suitablysupported by the side rails I I of the frame and in advance of ;thepower unit 211. :EX- tending upwardly from-ithe drive andpitchcontrol-unit -22 is-a vertical-mast :23, the;details of which willbehereinafter described.

The unit .222 comprises .:a EhOLlSl'DgiI-EA..S,VhlCh:.iS cylindrical andispositionedwith itsecentral axis -vertically disposed. #In one sidewallof the :housing is -a---bearin .25 which accommodates the drive shaft 2I In the top and bottomnendvvalls 25 and 2? bearings 28 and wereprovided. :These '-bearin-gs are-here indicated as being: anti-frictionbearings rotating around "the central vertical axis of the -mast 23. Thelower bearing 29 is;a combined radial and thrust bearing through whichaninner -tubularmast shaft '38 extends.

"Fixed upon this'shaft and restingupon the hearing Ed is a bevel gear 3!which is-in meshmwith a-bevel-p-inion '2. The bevel pinion is fixed arms39 upon the mast-head 38. As previously explained there is a constantangular relationship between the mast-heads. By this it is meant that inany given period of time one head will revolve clockwise the same numberof degrees that the other head revolves in a counter-clockwisedirection. Thus, as seen in Fig. l of the drawing, the mast-head 36rotates in the direction of the arrows a, and the mast-head 38 rotatesin -the direction ofztheyarrowseb. This of course is provided tostabilize the airplane and to counteract reaction forces set up betweenthe propeller structures and the power unit in the body of. the plane.The mast is rotatably supportedhnear its upper end by a bearing ring 56,"which is formed with ears M to receive pins 42. The pins AZ'eXtend.through eyes of brace rods 53 which extend outwardly and downwardly andare-fastened to the side elements II of the frame upon'the' drive shaftfl. The upper-bearingi 28 -circumscribes -a-n--outer-tub1.11ar =mastshah-.133.

This shaft carries an annular flange 3 lwhich -rests--upon-the'--bearing -28 and supports =the weight -of-' the outer-shaft 33. 1 -Abevel gear' 35 is -fixed on the lower end of theshaft' SE- and-is inmesh withthe'teeth-of:the pinion" 32. :Itwill *be'seen thatthetubularshaft :39 telescopes. within the tubular-shaft- 33-and thusprovides the mast structure indicated generally at 23. In view of thef-actth-atthe bevel'gears 3I and-35are of-the-same diameter-andare-disposed concentrical-ly of-the vertical axis of'the'mast, and forthe-furtherreason that=these gears are in simultaneous *me'shwith thedrive pinion-"32, it +will be seen that the tubular shafts 39 andliSwill rotate in opposite-directions around-a-cornmon vertical axis--atthesame speed.

Mounted upon the upper endof-theouter-tubular shaft' 33'isa mast-headedThis head has central passageway -'therethrough and carries an annularbearing structure 31 therein. Extending through the bearing-structure 37is the -upper -endof-the inner tubular-shaft'fiil-which is givensuitable radial-support by'the bearing. Mounted upon the upper end ofthe inner tubular shaft "*Bihis an uppermast head 38. Thus,the-mastheads-35 and 38 he in parallel horizontal; planes and rotatearound the central vertical-axis of 'the mast 23. By reference toFigs-:4 and-5 ofthe drawings it will be seen that-each of the mas-trheads 535 and 38 are formed with I diametrically =opposite-rigid radialarms' 39. =The'driving-gears' 3I and'135'are appropriately set withrelation to the driving pinion-32 so as to insure that the radial. axesof'the arms39 on themast+head"36 'will be at right'angles tothe radialaxes of the I8 by brackets M.

:The mast-headsziifi andrtlii; are-designed ;to; support propellerblades. -;The mast-;head--3Gcarries propeller blades: 45. and-46. zJThe;-mast:head 38 :carriespropellerjblades fill, and 43. ,As :shownlinFigs.': 8 andv .9- of: the drawings: these .blades. are "fitted with U-shaped.;bolting brackets deywh ich straddle".verticalawebs .55 (formin apa tiflfm h radial arms 39.jof each;:h.ea1d. jBoltsBI rsecure thebrackets in position and thus hold {the blades in a. permanentgrigidposition. ,gAS: shown i Eigs. .5, 6;and'.,7;:it will be scent-hatthexblades haveqa rigid portion 152 and. an articulate trailing ed e Therigid portion-:5Zand the articu atetrailing edge:have thezsectional formofzan airiQil, although ;the horizontals-width of the blade-:and itstrailing, edge is gradually reduced .towardath :tip of theblade.Theenteringwedgeofxtheportionsz52 presents agsurface of:semicircu1ar.crosssection. The ytrailingxedgerof the portion .52 terminates in wallextensions s54 .;betweenawhich horizontal whinge brackets 55 .are;.positioned. These brackets are secured .to :vertical-rbracezmemberssfifi; itibeing. understood thatthe-portion -52 ofthe propelleris of;shell-.like construction.

Atzthe rear. end of thezbracket-EE a, hinge pin-:51

.is vmounted. This extends through. hinge-;plate s 158:; which .arefastenediinto transverse slots. in the bodyofithe:articlllatetrailingledgefiii. Byreferenee .to- Figs... 6 .and it .will be. seen;thatithe :Thesmanipulation. :of thezaarticulate trailing edges 1 of:rthe .zpropeller :blades. produces :control of the cyclic totalandrdifferential pitchofzthe propeller. "It is "of: course. understood*thatitotal ipitch is 1 maintained by manipulating the propeller blades.around. their'zlongitudinalg axes: so. as to simultaneously increaseor" decreasezvthevpit h ofall of the blades. This-will-cause theiiftn ofall of the blades to increase ordecrease in unison so. that theaircraft-would either ascend or 5 descend, as.desire'd. lt ispossible-to obtain'this result by changing therate of rotationofthepropellers but this of course would-not produce total pitch variationsexcept when-the engineis operating.

In order to maneuver arr-aircraft ofthe helicopter type-and to'turn thecraft to-the right or left the drag on the'blades of one propellenunitmust be made greater than the dragon theblades "of theotherpropeller-unit. Thus the craft-willn5. turn by torque reaction in thedirection of the lesser drag. An increase of pitch of a propeller bladeincreases the drag, and conversely, a decrease of pitch decreases thedrag. When the pitch of the blades of one propeller unit is set toincrease the drag, and the pitch of the blades of the other propellerunit is set to decrease the .drag, the craft will turn in the samedirection as the direction of travel of the blades of lesser pitch. Thistype of pitch control will be herein designated as differential pitchcontrol.

It will be understood from the foregoing that total pitch control of ahelicopter of the type here shown will cause the craft to ascend ordescend, and that differential pitch control will cause the craft todeviate to the right or to the left from a straight course of travel. Itis also necessary to provide means for insuring lateral stability of theplane in its path of travel as well as to maintain it on its intendedcourse. In order to achieve these results it is necessary to vary thepitch of the blades at any point throughout the entire 360 degrees ofrotation of the blades around the axis of the mast. Thus if an airpocket should be encountered which would cause the aircraft to tilttoward one side, it would then be necessary to increase the pitch of theblade of the propeller on the low side while simultaneously decreasingthe pitch of the blade. on the opposite or high side. This will producegreater lift on the low side and will return the aircraft to levelflight. However, in the event it is desired to intentionally achievelateral movement of the aircraft it is necessary to tilt the aircraftintentionally in the direction of flight desired. This will cause theaircraft to move toward the low side, and this type of control of ahelicopter is known as the control of cyclic pitch.

In order to set the blades of the propellers dur' ing rotation of thepropellers to obtain total, differential, and cyclic pitch adjustment,each of the articulate trailing edges 53 is fitted with a bracket 59 towhich is connected an operating link 60. This link is pivoted to thebracket 59 at one end by a pin 6|. The opposite end of each of the linksis pivoted by a pin 62 to one leg of a bell crank 64. The bell crank ismounted upon a pivot 65 which is fixed to extend vertically from theupper face of the radial arms 39 of each of the mast heads 36 and 38.The opposite leg of each of the bell cranks 64 is provided with a pivotpin 66 which receives a link 61. The links 61, which are carried uponthe mast head 36, are connected by pins 68 with bell cranks 69. The bellcranks 69 are .disposed in vertical planes and are thus at right anglesto the bell cranks 64. The bell cranks 69 are mounted upon pivot pins Icarried by brackets II which project upwardly from the upper faces ofthe arms 39 of the mast head 36. The position of the brackets 'II iscontiguous to the cylindrical bearing portion I2 of the mast head 36, sothat the horizontal arms of the bell cranks 69 will extend throughopenings 13 in the cylindrical bearing 12 and will terminate in anannular space 14 which occurs between the tubular shafts 30 and 33 ofthe mast. These inwardly extending bell crank arms carry pivot pins 15to which the upper ends of operating rods 16 are connected. These rodsextend downwardly and are pivotally connected at I! to the inner ends oflevers 18.

Thelevers I8 are pivoted upon pins 19 carried by radially extendingbrackets fastened to the outer surface of the tubular shaft 33. Theouter ends of the lever arms 18 each carry a cam roller 8 I. Tensionsprings 82 act to urge the inner ends of the lever arms I8 upwardly andto urge the cam rollers 8I downwardly.

The cam rollers 8| rest upon the upper face of a cam ring 83. This ringis flat and has a central opening 84 through which the tubular driveshaft 33 extends. The opening is of sufficient diameter to provideclearance so that the ring 83 may have a vertical rocking action, ashereinafter described. Disposed at diametrically opposite sides of thering and projecting from the outer circumference thereof are trunnions85. These have bearings in a circumscribing gimbal ring 86 whichnormally lies in the horizontal plane of the cam ring. The gimbal ringis fitted in turn with diametrically opposite trunnions 81. Thesetrunnions are at right angles to the trunnions 85. The trunnions 8! arerotatably supported in the sides of bearing sleeves 88. The bearingsleeves 88 are an integral part of a crosshead 89 which is mounted tomove vertically as guided by crosshead posts 90. These posts areparallel to each other and to the central axis of the mast 23, and arefixed to the side frame elements II by suitable supporting brackets 9|.Mounted upon the crosshead 89 and beneath the assembled gimbal ring 86and the cam ring 83 are pulleys 92 and 93. The pulleys 92 are disposedupon diametrically opposite sides of the vertical axis of the mast 23and in the vertical plane of the crosshead posts 90. The pulleys 93 are.disposed upon diametrically opposite sides of the vertical mast 23 andin a vertical plane at right angles to the plane of the pulleys 92. Thepulleys 92 are provided with cables 94 which are led beneath the pulleysand are fitted with ball ends 95 resting in seats 96 in the upper faceof the cam ring 83 and at the upper ends of bores 91 through which thecables extend. The cables 94 lead forwardly and connect to opposite endsof a simple lever 98 which is mounted upon a vertical pivot shaft 99 atits center. Mounted upon pivot shaft 99 and extending at right angles tothe longitudinal center of the lever 98 is a lever arm I00. This arm isattached to cables I0! and I02 which, when pulled alternately, willcause the lever structure to rotate around the axis of the pivot 99. Theoperating means for the cables will be described hereinafter.

The pulleys 93 act as guides for cables I03. One end of each of thesecables extends upwardly through a bore in the cam ring 83 and is theresecured. The other ends of the cables I03 connect to the opposite endsof a lever I 05. This lever is mounted upon a vertical pivot I06. Thepivot I06 is in the form of a rod which extends through upper and lowerbearings I07 and I08 carried by the upper crosshead 89 and a lowercrosshead I09. The lower crosshead will be described hereinafter.Mounted upon the pivot shaft I06 is a lever arm IIO which extends atright angles to the longitudinal center of the lever I05. This lever armis provided with a rigid push-pull control rod III extending forwardlyto be operated by the pilot in a manner to be hereinafter described.

At the lower end of the pivot shaft I06 a lever H2 is provided. At thefree ends of this lever cables I I3 are attached. These cables leadaround pulleys H4 which are carried upon the lower crosshead I09 andagree with the cables I03 associated withthe upper crosshead 89. Thesecables are attached to diametrically opposite sides of a cam ring I I6.The cam ring I I6 is provided with trunnions II! which are carried in a'7 gimbal ri ng 11 8. The gimbahr'in .I tS isIfitted withhtrunnions l 19which are mountedrmzhearings formed. within bearingtmembers iliZG :whichare a par tnf'the crosshea'd |U9al1d Which-Te ceive the posts 98. The:crosshead Hi9 also carries pulleys 121. These pulleys are :upon=diametrically opposite sides of the eenter f the mast and receive-'c'ab1es 122. The :caio'les P22 connect =to I the cam rin'g I rs at theopposite isides thereof and are led'ior-Wa'rdly to a lever i -Z3 whichis fastened on the lower-end of the pivot shaft 99. It will thus be seenthat the alternate pullof the 'cabies ft and W2 will simultaneouslyswing the lever arms -9'8 and F23 to alter natly pull th'e-cables'l t.'Thiswill act to-cause the 1 cam ringsiis and"i'6 to rotate' upontheirtrunnions ES and II E, respectivelygand'thus will-dispose the camrings in parallel selected planes at an angle to the horizontal.

'The "movement of the push-pull'rod in either direction willroteitethe-pivQt shaft 168- and will alternately pull on cables Hi3 "and '3,respecti-vly, since the-ends of these cables are on the transversecenter *line occupied bythetrunnions fiii-and l l-i. A pull-on one'set-o'f these cables'will swing the girrlhal rings *86 and H8 upo'ntheir trunnionst? and H 9,-respectively.

The'lower cam ring H13 receives cam roller-s F2 2 carried upon leverarms 1 25. These arms are "mounted upon'pivot pins i -2'6 "which arecarried in'brackets 12 1. The brackets i z-l extend radially from*thecentral tubular drive shaft 39. The Walls ofthedrive shait,'asindicated at12'8, areslotted-to rec'eive'the innerends of the leversI25. "These ends are"pivotally connected at I29 toverticallyextendingoperating rods '30 which are led upthrough the center oi the tubulardrive shaft 30 and *pass through the mast-head 3-8, where they arepivotally connected*to 'belleranks l 3l. These bell-cranks aremountedoh-bracketS ['32 carried by'the mast-head 3'8 and are supportedbypivot pins 133. The free "arms "of the bell cranks 13'! arepivotallyconnected with links i34which in turn "connect with-the-'be1l=cranks fi iof the upper mast 'he'ad.

From the "foregoing it will '"be seen that the cam ring "83 "and-the'gimbal ring 85act through the cam rollers '8 i "ancltheir levers "F8 to"change the pitch of the blades i on the lower "mastheadd'fi.The'cam-ringHG and the-gimbal-ring I I8, acting through the-cam rollers-24*andthe levers l'25,'change'the pitch of the upper propeller bladesii carried'by the mast-head38. It will further be 'noted that "due to'the fact that the gimbal rings can be simultaneously tilted aroundtheirsupporting axes, andthat the camrings can be "simultaneously tiltedaround their supporting axes, the-angular'planeof the cam rings-Stand Htmay he set as-desired throughout the 360-degrace of a circle, of whichthe vertical axiso'f the mast is the center.

It is also desirable to simultaneously and alternately "vary the pitch0f the blades of the two propellers WithOlltchanging the settings of thegimbal and cam-rings. templates the simultaneous movement of thecrossheads $9 and 109 toward and away from each other tuponthe verticalcrosshead qaost $919. This is accomplished .by providing TIOSShEad'S 3-5which are mounted upon pins I35. The pins 136 are pivotazly tinounted'atthe ZflFifilldS of "lever arms I31. These *arms extend horizontally .andare apart of bell cranks I38. The bell cranks have verticalarms I3 9 towhich' push-pullrods 'l w are connected. The bellcranks'arapivotallyThis manipulation eonmountediupon :a :shaft Ml :whi'ch :exte'mds' I horizontally' and is "supported transversely fheneath the gear :hon'sing 26"in'ibearings 1&2. It is' intended that *when the :push-zpullirods H4092118 operatedzthezarms l 3-1Wvill'1oscillate .directlyiand ivillzraiseand slower the pin [3 B'avhich CEI'I'iGSitl-LB cross :levers r35. Thisraises "and lowsers cnoss- .heads SQ a'nd '09 through'rod 140, "thelever 1311 andlth'e member #35. The :cross levers have two diametricallyextending -zarins 1'43 "and hi'davhich usually stand in the-ve'rticaltplane :o'f thesaxis ofipin 5136. "At the free ends rof'zthesescrossalevers operating cables Md and a l 46 are :connected. 'Thecrossilevers salso'thavefhorizontallyiextending arms 1' 8? and 1'48iTh'ese arms :are at right angles lto :the (previously mentionedWertioa'l arms. The arm fill Bis provided'awith :"ailiITk l 49' WhiGhliSi pivotecl tozth'eialm at 1'58 and extends upwardly :to the crosshead"89 where it is *pivotediat il' t l ilO'Jbh'B crosshead. The'axis of thepivotiszinithexver tical .pi'aneoi' the axis of the shaft I86 fan'dzisthereabove. Th'erfre'e .end iof the' arm 5 48 :is provided With'a pivotrs-2 to which ailinkilr53 is connected. This filinkiextends downwardlyand is secured to vthe Blower ":cresshea'd 2109, where :it :isc'onne'cted by a=pivot pin"1l'54. lThe :ax-is'nf the pivotzpin ti l-isalso in i'thevertical plane- 10i :the axis .of the pin il-SG. It willzthus theiseenlirom this arrangement that :am alternate rpull Jon :thecables 11*45' or Hi6 will :tend "tormotate 17116201 055 levers l3Earounditheiriaxes rand azvill'iactito xiralw the *crossheads 89 .iand W9toward each .other or to separate them siimiltar-reously.

The controls forithestructureidesorihediin'ithe foregoing specificationaretpreierahly :Iocated tin advance I'Of thB pilots seat 155. Here :itwillibe seenth-at :a-itransverseiframe member li8zis provided. Thisiiramein'iemher istcylindricaliaritl ex= tends horizontally "betweenposts 1156 projecting vertically rand :locate'd substantially cover'zside frame members l'l. Rotatahly isupported upon the memberil 3 iszatubular torque-tube :I'E'l ZThis 'tllbe is freeito rotate .OIl: themember "'I fi8zarid-1earries diametrically oppo'site extendingitrunnio'ns- T58 upon "which f'a TfOI'k I59 is r'mounted. The trunnionsare longitudinally ialig'ned' upon. whorizontal: axis extendinglongitudinally of stherframe. The -fork istthus free Ito swing faroundits "trunnions "in a *transversewver'tical plane. ."zlo'r .za'c--comp'lishing this afhandle lfiuaextendszupwardly from the forkrandfisprovided2at upper end .with aiipair .df :rshaped grips 31 61 The-handle:16'0 i is mounted "within the f ork smember 1518 so that it canirritate upon its l'ongitudin-al :axis. f-lvl'ounted:upon the handle iHi 0 iandiseouredtthere- :totatmdints sabove the fork il'5i8carearouateiarms 162 and "it 63. These warms :zexterrd downwardly andaconoentrioally witharelation-iaoitheihorizontal axis -:of athB torquetube #5?! andtterminaterupon opposite sides ofitheitorqueZtubeiand inthe-plane of :the axis thereof. "Connected moithearms L162 and-iififlzarestheocables il 45rand-?M6. :Thesecables zareiled around pulleysffiland [65, respectively, 'therpu'lleys fleeing carrieditbyrthezposts1:58. Thus, as thescontrolrhandle I isrrotated up'onitsilonigitudinal-naxis by -the T-handle igrips W1 ithe rcross levers l-35 lWill he operated isimul taneous'ly around the iaxis (if the :pin 36rand:- vvill athu-s .simultaneously :move the crossheads 89 ian'd I 69'toward andfaway from-:eachccther, aszguided upon the aposts '90.:Se-cured ito the upper end 61" "the Ifoi'k H39 eare lthe wabl'es UJIand 02 whieh aie :conn'ected .to "the lever \arm MIO desi-gned i-to actuate the lever ieaandzto dispose thegimbanings 1Q rand H 3 at a'desired angle 430 61163 horizontal.

Carried by the torque tube and extending downwardly therefrom-is a rigidlever arm I66, to the free end of which push rod III connects. Thus,when the handle I 60 is moved forwardly or rearwardly the torque tubeI51 will rotate on its longitudinal axis and will actuate the lever armH and the shaft I06. This in turn will act through the levers I and I22and the cables I03 to tilt the cam rings 83 and IIS to a desired anglerelative to the horizontal. It is to be understood that irrespective ofthe tilted position of the cam rings the springs 82 and I61 will act tohold the cam rollers BI and I24 against the faces of the cam rings.

Mounted in convenient relation to the operating handle I 60 is a pitchlever I 68. This is carried on a horizontal pivot pin I69 supported onthe frame of the aircraft and has a downwardly extending lever portionto which the pushpull rod I 40 connects. Ehus as the pitch lever I68 isswung around its pivot I68 the bell crank I31 will be actuated to raiseor lower the pins I36 which carries the cross levers I35. By thisarrangement the crossheads 89 and I09 will be simultaneously raised andlowered regardless of the distance they are spaced apart by the actionof the cross levers I35 and regardless of the inclined setting of thegimbal rings and the cam rings.

It should be pointed out that the mounting of the propeller blades uponthe mast heads 36 and 38 is such that the blades will be inclinedupwardly. The dihedral angle here indicated is approximately threedegrees, although I do not wish to be limited to this degree. The ribswhich extend downwardly on the masts from the blade supporting portionsare inclined at an angle which gives an optimum setting forauto-rotation in the event of power failure to the vertical and in thedirection of travel of the mast heads.

In operation of the aircraft as here disclosed the power unit 20 is setin motion to drive the shaft 2I. This shaft in turn acts through thedriving pinion 32 to simultaneously drive the gears 3I and 35 inopposite direction. As has been explained previously the gear 3I isfixed to the inner tubular drive shaft 30 of the mast, and the gear 35is fixed to the outer drive shaft 33 of the mast. Suitable conventionalcontrols are provided for the power unit but are not indicated in thedrawing, since their operation would be obvious. Suffice it to explainthat the tubular drive shafts 30 and 33 will drive at uniform speed andthat the speed may be accelerated or decelerated at the will of thepilot. It will be assumed that while the aircraft is standing on theground and its power unit is in operation the cam rings 83 and H6 andthe gimbal rings -86 and H8 will be properly aligned in parallelhorizontal planes at right angles to the vertical axis of the mast, andthat furthermore, the articulate trailing edges of the blades will be inthe position shown in Figs. 6 and '1 to provide an air foil, the contoursurface of which is continuous. When the gimbal rings and cam rings arethus aligned the levers 98 and I05 will stand in the positions shown inFig. 10 of the drawing, and the lever arms I00 and H0 will stand atright angles to each other. At this same time the crossheads 89 and I09will be spaced in their normal relation to each other with the leverarms I 41 and I 48 of the cross levers I35 standing horizontally, andthe pin I36 lying in the horizontal plane of the pivot shaft I4Icarrying the bell cranks I31. When it is desired to ascend the pitchlever I68 is swung forwardly.

10 This will pull on the push-pull rod I40 and will swing the pin I36upwardly. Thus, the gimbal rings 89 and I09 will be liftedsimultaneously. They will then act through the cam rings 83 and H6 toforce upwardly on the cam rollers 8| and I24. This will pulldownwardly-upon the operating rods 16 and I30 and will swing the bellcranks 69 and I3I and pull upon the links 61 and I34 of each mast-head.The links will swing in the direction of the arrow 0, as indicated inFig. 4, and will force the links 60 in the direction of the arrow d.This will cause the articulate trailing edges to swing downwardly upontheir pivot shafts 51 and thereby simultaneously increase the pitch andthe lift of all of the propeller blades so that the aircraft willascend. When the aircraft has reached a desired elevation the pilot maylevel off for flight by manipulation of the control lever I60. When thecontrol lever is rotated upon its longitudinal axis by the handle gripsI6I the cables I or I46 will be drawn as the arms I62 and I63 rotatearound the axis of the handle I60. This will pull on one of the cablesand pay out on the other cable. The arrangement of the cables I45 andI46 and the arms I62 and I63 is reversed on opposite sides of thecontrol mechanism so that the two cross levers I35 will rotate in unisonand in the same direction. When the control lever I is rotated aroundits longitudinal axis the cross-heads 89 and I09 will be drawn toward oraway from each other, depending upon which way the control 1ever I60 isrotated. It will be seen that this action will take place regardless ofthe previous setting of the cross lever pin I36. This manipulationcauses one set of propeller blades to have greater pitch than the otherset and causes the aircraft to turn to the left or right, depending uponwhich set of blades has been given the greater amount of pitch. When thecontrol lever I60 is pushed forwardly or drawn rearwardly the push-pullrod III will be actuated. This will tilt both of the cam rings 83 andIII; to give a fore or aft movement to the plane. When the operatinglever I60 is swung to the left or right upon its pivot pin I=58 thecables IIII and I02 will be alternately drawn or paid out. This willswing the.

shaft 09 and act through the levers 98 and I23 to tilt the gimbal rings86 and 8 around their axes and will cause the aircraft to move in thedirection the operating handle I60 is moved. While the presentdisclosure of the invention does not include any means for temporarilysetting or holding the levers I60 and I68 in desired set positions it isevident that such means can be provided, and that they would be withinthe scope of the present invention.

It will thus be evident that the aircraft may be manipulated to move inany direction, and that since the cam rings 83 and H6 may be inclinedaround the axes of their trunnions, which ar at right angles to thelongitudinal center of the plane, the articulate trailing edges of thepropellers on both mast-heads will automatically feather as themast-heads rotate and, as the cam rollers traverse the cam surfaces ofthe cam rings.

In order to bring the aircraft to a safe landing the controls may berestored to their original neutral positions and the plane may belowered to the ground by proper manipulation of the pitch lever or ballowing the propellers to rotate under the force exerted by the airpressure as the plane drifts downwardly.

It will thus be seen that the aircraft of the helicopter type here shownprovides a strong and durable structure: 111; which: the? propeller:blades are mounted upon the :mast -h'eads: rigidly; thus eliminatingdangerous pivotal connections; the-ia-ircraftbeing further providedrwithsimple and: directxcontrol' means whereby cyclic; dif:-- ferenti'al:and-totalupitch may be easily establishedaiand controlled atall'..times.

WhileLsI havetshown the preferred form of my' invention'a's nowknownztorne, it'will be un'I-' derstoodthat various changes may bemadel-in combination, construction; and arrangement :of parts by those?skilled: in the art, without departing from-.1 the spirit of theinvention" as. claimed;v

Havingithus'tdescribed my invention. what I claim? and desire to: secureby Letters Patentristzi I; In: an: aircraft of the I helicopter type, abody; structure; a a vertical mast'imounted there om'and including atubular rotatable drive :shaft; asmast headv fixedon. the upper" endthereof, a+:plurality of; variable pitch propeller blades mounted upon'said 'head, actuating means be= tweenirthe propeller blades andthe-headwhere by variable pitchcan be attained; operatingro'ds connectedwith said actuating means and ex-' tending: downwardly through thetubular drive shaft; cam levers extending through the wall of the driveshaft" adjacent the lower end thereof and mounted pivotally-- uponsaiddriveshaft upon axes'at right angles to thelongitudinal axis of thedrive sha'ft and disposed diametrically" with relation thereto; theinner ends of said levers being attaohed'to said operating rods, camrollers carried at the outer ends of said levers," a" cam ringcircumscribing' said drive shaft and'with Wl'llCh'llhG cam' rollersengage;- anda mountingfor said ring adapted'to sup:- port'thez ring andpermit itto move'b'odily and longitudinally of the: drive :shaft totiltthe ring" fore'andaft of said drive shaft and to tilt the. ring fromside to side.

21 In an aircraft of the helicopter type a'.

body, structure, a vertical mast mounted .thereonincludinga pair.oftubular drive shafts telescoping' one within the other, a rotatablesupport for. said masts, driving means for saidtubulari'd'rive shaftswhereby, theywill rotate in opposite directions around acommonaxismastheads one fixed upon the upper end of each of said. driveshafts, a pluralityof variable pitch propeller blades mountedupon eachof said mast heads, operating means mounted uponeacha ofsaidTmast-rheads and assooiatedwith the pro-. pelle'r blades carriedthereby for varying their pitch, control rods for each. of said,"operating means extending downwardly,throughwttlie tue bular driveshafts, a set of'cam lverspivotally mounted upon the outermosttubularldrive shaft and extending through the wall thereof, the.inner'ends of said cam levers being connectedto. thecontrol rods.extending, from the mast-head carried by said outer drive shaft, saidcamlevers being disposedin a transverse plane above the.

power drivingmeans, the outer ends of'said cam levers oarrying camrollers, a set of camleversn last-named; setpf. levers, a, pair of: cam:rings; 7 6

one disposedirra plane above-the driving means:-

and engageds'by the rollers carriedilbythe uppers cami levers; theuotherdisposed'lin. a .planebe; neath the driving means and: engagediby' the 1rollers carried by the lower cam levers, said cam 1 which the'cam ringsarepivotally mounted-upon:

axes extending longitudinally of the" aircraft body, a pair ofsupporting members: for'the gimbal rings and by -which the gimb'al ringsare pivotally mounted on transverse axes at right" angles to the axes ofthe-cam: rings, rigid f-rame members upon which' the gimbal ring:supports are mountedfor'axial movement, means con--- necting said'gimbal ring supports and"whereby= said supports may he -axially movedin opposite directions, means supporting said connecting v means wherebysaid axialsupports may be ax ially moved simultaneously in the samedirec-- tion without disturbing th'eir'spacing; meansfor tilting thegimbal rings aroun'dtheir pivotal axes; and means for tilting the-camrings around their pivotal axes."

3. In an aircraft-having 'a mast including a pair oftubulandrivihgshaftS telescoping one" within the other and carryingpropellers formed with variable pit'cHblades at the upperen'ds of tingmeans'and extending outwardly from the" mast, the outer 'f'r'ee -ends=of 'said 'actuating"le=-- vers being disposed" at different levelsonthe" mast whereby theywill travel in parallel" planes around the centralaxis ofthemast'as'the mast rotates, cam rings; one fortl'l'e actuatinglevers" cam rings; a-pair'of vertically movable supports;-

one for' each camring, apair of gimbal' rings, onedisposed between each"vertical j support 'andf a corresponding' cam ring wherebythe"p'iv'otal"axis of the'cam ring-upon the 'gimbal "ring will' be'longitudinally ofthe aircraft and the pivotal" axiszofthegirnb'al ring will be at rightangles thereto; control means connected withthe gimbal' rings and thecam 'rings' whereby said gimbal rings and the'cam rings 'may be tilted'simul tane'ously or separately; an articulate connection between-thevertically-"movable supports whereby"said "supports maybe movedsimultaneously' toward- "or away: from eachother, control" meansconnected with: said vertically -movab1e supports;

and: control means associatedwith said articu late connection wherebythe vertical movable supports 'may be moved simultaneously in thesame'directi'on irrespective of their'spacing.

421 The structure' of claim 2 wherein a'single saidrings:

5'. The structure of'clainr 3 including a single operatingmember, meansconnecting said single operating'mem'berwvith the cam rings andthe'gimbal rings whereby movement of saidsin gle'o'per'ating member maysimultaneously' an'd'l' separately operate said rings.

HAROLD D. HARBYI' (References on following page) REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS 5 Number Name Date 1,524,309 Perry Jan. 2'7, 19251,697,009 Isacco Jan. 1, 1929 1,836,406 Smith Dec. 15, 1931 1,896,511Goldman Feb. 7, 1933 10 Number 14 Name Date Pescara May 30, 1933Gerhardt July 11, 1933 Wick Dec. 5, 1933 Wilford Dec. 24, 1935 Cox Feb.12, 1946 Bossi Mar. 5, 1946 Trice Apr. 23, 1946 Thomson Nov, 5, 1946Bendix Dec. 14, 1948

